Thuridilla splendens? from Great Barrier Reef

October 31, 2005
From: Rachel Murphy

Hi Bill

I haven't posted anything in a while but seeing the discussion about Daniel Footes photo of a Thuridilla sp [#15079] has prompted me to get off my bum. I got to meet Daniel recently and it was great to meet a fellow enthusiast.

Locality: Bowden Reef, Great Barrier Reef, Queensland, Australia. Depth: 8 m. Length: 2-3 cm. 8 September 2005. reef top. Photographer: Rachel Murphy

I think it is similar to the photo by Nishina Masayoshi [#3108]  which was identified as Thuridilla splendens. I am confused though by the distinct lack of spots compared to other messages for that species. This was the only individual I saw. It was quite active moving about - is it coral or a sponge?


Murphy, R.M., 2005 (Oct 31) Thuridilla splendens? from Great Barrier Reef. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Rachel,
With the proviso that I might have it quite wrong, it seems to me that T. splendens has a colour pattern which has two main variables. In Yukari Sato's message[#11398] the photos are identical in colour to Baba's original illustration, which we need to consider the 'standard', just in case there is more than one species involved. Species from Japan all appear to have this colour pattern. However in animals from the central and south Pacific the white areas become bright blue, and the yellow lines and spots can change. In messages from Hugh Dickson [#12026] and Vinka Stenhouse [#1567], both from Vanuatu, the yellow lines near the parapodial edge are replaced by spots. In Nishina Masayoshi animal from Papua New Guinea [#3108], and yours from the Great Barrier Reef, the lower yellow spots have become lines

One problem with this transition is that while Japanese speciemens have longitudinal lines along the rhinophores, the colour pattern is quite different in the blue pigmented animals from the south pacific. However Bruce Potter's photo [#4358] may represent an intermediate, with small yellow spots aranged in lines. So I guess at this stage I will consider this to be T. splendens, but hopefully we will get some more photos to compare from other participants.
Best wishes,
Bill Rudman

Rudman, W.B., 2005 (Oct 31). Comment on Thuridilla splendens? from Great Barrier Reef by Rachel Murphy. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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